It is known that a silane is necessary as a component of rubber mixtures which are vulcanizable with sulfur and contain a rather high portion of silicate fillers such as e.g. precipitated silicic acid, in order to impart sufficiently good properties to the vulcanizates.
Published German Patent Application DE-AS No. 23 19 638 describes how valuable vulcanization products are produced from rubber mixtures containing silicate fillers, halogen-containing rubber grades, and certain halogen-containing silanes.
Such mixtures frequently contain thioureas as vulcanization accelerator.
However, the latter, and also the breakdown products produced from them during vulcanization, are considered to be toxicologically hazardous. (Eholzer, Kempermann in "Gummi, Asbest, Kunststoffe" [Rubber, Asbestos, Plastics] 36 (1983), p. 9)